Transducing head mount apparatus

ABSTRACT

An arrangement is disclosed for supporting a transducer head on an air bearing. The system includes a planar three point resilient suspension system. The suspension system when acted upon by the air bearing deflects to form a parallelogram support for the transducer which provides desired mobility of the transducer.

United States Patent Robitschek June 6,1972

[54] TRANSDUCING HEAD MOUNT APPARATUS [72] Inventor: George ConradRobitschek, Los Angeles,

Calif.

[73] Assignee: RCA Corporation [22] Filed: Dec. 7, 1970 211 Appl. No.:95,778

[52] U.S. Cl ..340/l74.1 E, 179/100.2 P, 248/204,

267/158 [51] Int. Cl. ..Gllb 5/60 [58] Field of Search ..179/100.2 CA,100.2 P; 248/24,

[56] References Cited UNITED STATES PATENTS 3,055,987 9/1962 Ricketts..179/l00.2 P 3,069,667 12/1962 Doody....

3,593,326 7/1971 Turner...

Primary ExaminerBemard Konick Assistant ExaminerL. Russel GoudeauAtt0rney-Edward J. Norton [57] ABSTRACT An arrangement is disclosed forsupporting a transducer head on an air bearing. The system includes aplanar three point resilient suspension system. The suspension systemwhen acted upon by the air bearing deflects to form a parallelogramsupport for the transducer which provides desired mobility of thetransducer.

5 Claims, 4 Drawing Figures PATENTEDJUH 6 I972 3,868,668

SHEET 2 or 3 Jm/ew for: 650/765 61 flaw/waif AYfarliay TRANSDUCING HEADMOUNT APPARATUS This invention relates to apparatus for supporting asignal transducer with respect to a recording medium, and is especiallyuseful where there is relative motion between the transducer and therecording medium.

The apparatus to which this invention relates is particularly, althoughnot exclusively, adapted for use in combination with tape, drum or discmagnetic recorder-reproducer systems used as memory storage devices incomputing machines and the like.

In the operation of systems where the recording medium moves relative tothe transducer, it is desirable in some applications to space thetransducer close to but not in contact with the recording medium. Thisclose spacing is particularly important in systems where the recordeddata is in the form of magnetic bits, since the spacing between therecording medium and the transducer determines the maximum bit densityand hence the storage capacity than can be achieved. Conversely,continuous or prolonged contact between the transducer and the recordingmedium produces undue wear, the accumulation of dirt and results indegradation of the recorded signal.

It is well known that the rapid relative movement of the recordingmedium and transducer generates a laminar flow air or gas fluid layerbetween them. The rapidly moving fluid layer may be used to cause atransducer to fly or float at a given distance from the recordingmedium. The prior art discloses methods by which signal transducers maybe caused to fly" by utilizing a fluid bearing. However, many problemsare encountered in devising practical means for controlling the relativeposition of a transducer and a recording medium. High relative speed maymake many arrangements susceptable to acceleration forces that can beinduced by vibration and positional changes. These forces may result inerratic positioning of the transducer and even undesirable crashing ofthe transducer on the surface of the recording medium.

To cope with such problems, transducers supports have been devised usinggimbals or multiple springs arranged in separate planes. The gimbalapparatus may be of a conventional pivotal type or a planar springhaving orthogonally arranged portions. This permits movement of thetransducer about axes both parallel and perpendicular to the directionof relative motion of the transducer and record medium. While it isdesirable to allow motion of the transducer with respect to therecording surface to permit the transducer to conform to the airbearing, this motion should be selective. That is, rotation of thetransducer should be permitted about an axis which is in the directionof relative motion with the recording surface. But rotation of thetransducer should be avoided about a second axis normal to the firstaxis and lying in a plane parallel to the recording surface or a tangentto the recording surface where it is of the drum shaped type. It is themotion about the second mentioned axis which is the problem encounteredwhen utilizing the gimbal or multiple spring arrangement of the priorart.

In the arrangement of the present invention, a three point planar springsuspension is provided to mount the transducer such that it remainsparallel to its initial position. That is, the flat spring elementswhich mount the head are three parallel arms that form a trueparallelogram suspension, in which the arms remain parallel to oneanother as the head rides along the bearing. While the head can tilt orrotate about an axis through the transducer which is in the direction ofrelative motion of the transducer and recording surface, this axisremains parallel to the recording surface or tangent thereof and alignedwith the recorded information track.

FIG. la and b are a plan view and side elevation view respectively of aportion of the transducer suspension arrangement of the invention.

FIG. 2 is a comprehensive perspective view of the support system for atransducer according to the invention.

FIG. 3 is a side elevation view of the support arrangement of FIG. 2showing the transducer and suspension system in operative relation witha fluid bearing formed by the movement of an adjacent recording medium.

In FIGS. 1a and b there is shown a three point suspension assembly 2.The suspension assembly 2 has a plurality of interconnected portionswhich lie in a common plane in the absence of a stressing force at anangle to the common plane. The assembly 2 comprises an open frame member4 surrounding a slotted portion 6 through which a transducer, not shown,may be mounted.

The slotted portion 6 is coupled at one end 7, to opposite portions 8and 10 of the open frame member 4, by elongated web members 12 and 14.The members 12 and 14 are resilient generally Z-shaped elongated webseach having a relatively long central portion 16 and relatively shorterend portions 18 disposed generally transverse to the central portion 16.At the end 20 of the slotted portion 6, there is coupled a thirdresilient elongated web member 22 extending away from the portion 6 in adirection generally parallel to the central portion of the members 12and 14, and secured to a further portion 24 of the open frame member 4.

Also as shown in FIGS. 1a and 1b, the assembly 2 has a planar portion26, which is disposed substantially normal to the open frame member 4and is preferably an extension thereof. The portion 26 is utilized inmounting the suspension assembly 2 to further portions of acomprehensive support structure as hereinafter shown and described. Theaxes indicated as 28 and 30 indicate a preferred orientation of theassembly 2 with respect to a relatively moving record medium. The axis28 is in the direction of relative movement of a recording medium andthe suspension assembly 2, with the axis 30 transverse to suchdirection.

In practice of the invention the assembly 2 is preferably fabricatedfrom a single piece of resilient non-magnetic material such asberyllium-copper or plastic. The assembly 2 may be fabricated byetching, stamping or otherwise machining a piece of the describedmaterial into the form shown in FIGS. la and 1b. An overall length L of0.337 inches, width W of 0.175 inches and thickness T of 0.002 inchesfor the assembly 2 of FIG. 1 has been found suitable in practicing theinvention. The elongated web members l2, l4 and 22 preferably are of thesame longitudinal dimension A. For the overall dimensions L, W and Tgiven, a typical dimension A of 0.110 inches is suitable. The width B ofthe members l2, 14 is typically half or 0.010 inches the width C of themember 22, while the dimension D of the open frame member 4 is typically0.030 inches. The slotted portion 6 may be approximately 0.160 incheslong and 0.050 inches wide with a slot 0.l 15 inches by 0.010 inches.

In FIG. 2 there is shown a perspective view of a preferred completetransducer support arrangement. The member 32 and 34 form a shroud orenclosure for the transducer head core 36. Each of the members 32 and 34are affixed at one end to a housing or main support member 38, withtheir free ends being spaced apart by approximately the width of thesuspension assembly 2. In practice of the invention, the housing 38 ismounted in fixed relative relation with a recording medium by suitablemeans not shown. As shown and described with regard to FIGS. la and b,the suspension assembly 2 includes an open frame member 4 surrounding aslotted portion 6 which is intercoupled with the frame 4 by the membersl2, l4 and 22. As shown in FIG. 2, the external periphery of the frame 4and angle portion 26 of the assembly 2 are secured to the members 32 and34. This is accomplished by bonding or means such as a groove, notshown, in the free edges of the members 32 and 34. The end portion ofthe head core 36 which contains the transducing gap 40 is mountedthrough the slotted portion 6 of the suspension assembly 2. The gappedend of the head core 36 is captively held in a slot 42 of a pad member44 and is preferably flush with the end or working surface 46 thereof.The pad 44, which for example may be a non-magnetic ceramic, has its end47 fixedly secured by known means to the slotted portion 6 of thesuspension assembly 2, thereby rendering the portion 6 itselfsubstantially rigid.

The axis 28 indicates the preferred direction of movement of a recordmedium, not shown, past the surface 46 containing the transducer gap 40of the head core 36, with the axis 30 transverse to that direction.Leads 48 are shown extending to and about the head core 36 fortransducing suitable signals.

FIG. 3, in which like reference elements correspond with those shown anddescribed with reference to FIGS.1a and b and 2, shows the transducerhead 36 and suspension system 2 in operative relation with a fluidbearing indicated generally by the arrows 50. The fluid bearing 50 mostcommonly an air bearing, is produced by the movement of the recordingmedium adjacent the pad 44. The recording medium, or tangent thereto ifit is a drum 52, is diagrammatically represented by the line withreference character 54. The air bearing exerts a force on the suspensionassembly 2. The force which is in the general direction of air bearingarrows 50, is transmitted to the slotted portion 6 through the pad 44and core 36 which are secured to the slotted portion 6. As shown in FIG.3, the slotted portion 6, which is prevented from bending by theattached rigid pad 44, is deflected or translated out of the rest orcommon plane of the assembly 2 with the portion 6 and working surface 46remaining substantially parallel to the axis 28.

The members 12, 14 and 22 remain secured between the members 4'and 6.However the relatively shorter portions 18 of member 12 and 14 arerotated or twisted in torsion and the extremities of the member 22 arerotated or flexed by the acting force of the air bearing 50. Therelatively longer central portions of the member 12, 14 and 22, whileretaining their substantially straight or lineal shape, form the sidesor legs of a parallelogram shaped support. The assembly 2, while beingresilient to facilitate the formation of the parallelogram, is chosenandproportioned in length, width and thickness such as that indicated,to prevent buckling or lineal elongation in this stressed condition. Thetransducer head 36 mounted to this parallelogram type suspension isthereby rendered free to move up and down in the direction of the airbearing 50 and has restrained rotation about the axis 28. This is due tothe flexing and/or twisting at the connecting points of the portion 6 towhich the transducer 26 is coupled, and the members 12, 14 and 22. Thetransducer head 36 is however prevented from rotating about a transverseaxis such as 30, shown for example in end view in FIG. 3. This is due tothe fact that, while as indicated the members 12, 14 and 22 form aparallelogram in which the sides are deflectable at their ends, theintermediate portions of the members 12, 14 and 22 do not buckle orchange their lineal dimensions.

Thus an improved self-aligning support and suspension system is providedin which the transducer head has desired mobility for following an airbearing, but wherein undesirable rotation of the transducer isprevented.

What is claimed is:

1. Apparatus for supporting a transducing head, comprising:

a first member to which said transducer may be fixedly mounted,

an open frame,

first and second generally Z-shaped elongated resilient web members,each having a relatively long central portion and relatively shorter endportions,

one end of each of said Z-shaped members, being coupled to a first endof said first member, the other ends of said Z-shaped members beingattached to opposite portions of said open frame, and

a third elongated resilient web member extending away from said firstmember in a direction parallel to the central portions of said first andsecond members, said third member coupling the other end of said firstmember to a further portion of said open frame.

2. The invention according to claim 1, wherein said first member, saidopen frame and said first, second and third elongated resilient membersare relatively thin planar members which form with said open frame asuspension system for a transducer, said suspension system in a firstcondition thereof having said first member and said elongated membersdisposed substantially in a common plane with said open frame member,said suspension system assuming a further condition in response to aforce applied to said first member, in which said first member isdisposed in a further plane parallel to said common plane with thecentral portion of said elongated resilient members being deflected toform substantially parallel arms intercoupling said first member withthe open frame member in said common plane.

3. Apparatus for positioning a transducer with respect to a recordmedium in response to a fluid bearing formed by the relative movement ofthe record medium with respect to said transducer in said fluid,comprising:

a first support member fixedly mounted in spaced relation with saidrecord medium;

a second planar member to which said transducer may be fixedly mountedin a manner to render said second member substantially rigid;

a generally rectangular planar open frame member surrounding said secondmember;

means for deflectably mounting said second member to and in the plane ofsaid open frame member, said means including first and second generallyZ-shaped resilient planar members, each having a relatively long centralportion and relatively shorter end portions, one end of each of saidZ-shaped members being coupled to a first end of said second member, theother ends of said Z- shaped members being coupled to opposite portionsof said open frame, and a third resilient planar member extending awayfrom said second member in a direction parallel to the central portionsof said first and second Z- shaped members, said third member couplingthe opposite end of said second member to a further portion of said openframe; and

means for mounting said open frame member to said first support memberin a manner which allows said second member to be deflected out of theplane of said open frame in response to a force. applied thereto by saidfluid bearing.

4. The invention according to claim 3, wherein said open frame member,said second member and said means for mounting said second member, formportions of a single piece of resilient material.

5. The invention according to claim 3, wherein the central portion ofsaid first and second Z-shaped members are disposed parallel to a firstaxis in the direction of relative motion of said record medium and saidtransducer, so that said second member and hence said transducerexperiences restrained rotational motion about said first axis but isinhibited from rotational motion about a further axis transverse to saidfirst axis.

1. Apparatus for supporting a transducing head, comprising: a first member to which said transducer may be fixedly mounted, an open frame, first and second generally Z-shaped elongated resilient web members, each having a relatively long central portion and relatively shorter end portions, one end of each of said Z-shaped members, being coupled to a first end of said first member, the other ends of said Z-shaped members being attached to opposite portions of said open frame, and a third elongated resilient web member extending away from said first member in a direction parallel to the central portions of said first and second members, said third member coupling the other end of said first member to a further portion of said open frame.
 2. The invention according to claim 1, wherein said first member, said open frame and said first, second and third elongated resilient members are relatively thin planar members which form with said open frame a suspension system for a transducer, said suspension system in a first condition thereof having said first member and said elongated members disposed substantially in a common plane with said open frame member, said suspension system assuming a further condition in response to a force applied to said first member, in which said first member is disposed in a further plane parallel to said common plane with the central portion of said elongated resilient members being deflected to form substantially parallel arms intercoupling said first member with the open frame member in said common plane.
 3. Apparatus for positioning a transducer with respect to a record medium in response to a fluid bearing formed by the relative movement of the record medium with respect to said transducer in said fluid, comprising: a first support member fixedly mounted in spaced relation with said record medium; a second planar member to which said transducer may be fixedly mounted in a manner to render said second member substantially rigid; a generally rectangular planar open frame member surrounding said second member; means for deflectably mounting said second member to and in the plane of said open frame member, said means including first and second generally Z-shaped resilient planar members, each having a relatively long central portion and relatively shorter end portions, one end of each of said Z-shaped members being coupled to a first end of said second member, the other ends of said Z-shaped members being coupled to opposite portions of said open frame, and a third resilient planar member extending away from said second member in a direction parallel to the central portions of said first and second Z-shaped members, said third member coupling the opposite end of said second member to a further portion of said open frame; and means for mounting said open frame member to said first support member in a manner which allows said second member to be deflected out of the plane of said open frame in response to a force applied thereto by said fluid bearing.
 4. The invention according to claim 3, wherein said open frame member, said second member and said means for mounting said second member, form portions of a single piece of resilient material.
 5. The invention according to claim 3, wherein the central portion of said first and second Z-shaped members are disposed parallel to a first axis in the direction of relative motion of said record medium and said transducer, so that said second member and hence said transducer experiences restrained rotatiOnal motion about said first axis but is inhibited from rotational motion about a further axis transverse to said first axis. 